The waste may be food waste; fresh, potable water (white water); water from domestic equipment other than toilets, e.g. bathtubs, showers, sinks, washing machines, etc. (greywater); or sewage and/or sewage water (blackwaste).
If a sanitary item, such as a sink, shower, toilet, etc. is installed close to or below the level of a drain pipe, the gravitational force acting on the waste to force it along the drain pipe may be low or even negative, i.e. insufficient to cause the waste to flow along the drain pipe. To overcome this problem, waste may pumped along the drain pipe by a pump activated when there is waste to be moved.
A macerating toilet uses a grinding or blending mechanism to reduce human waste to a slurry, which can then be moved by a pump. An electric pump is most often used to pump the macerated slurry into a sewage system.
Macerating units not for use in macerating toilets may be provided by ultrasonic devices. Ultrasound disintegration of sewage sludge is a macerating water treatment technology. The ultrasonic energy subjected to the sewage mechanically destroys both bacterial cells and difficult-to-degrade organics.
The disadvantage of the above described pumping mechanism is that the pump is noisy due to the powerful pumping required to pump the slurry. The pump is required to be operated during the period that waste is being moved along the sewer drain pipe.